Typically, as locks used for living accommodations and security purposes and installed on doors so as to restrict visitor access, various types of door operating devices (key/lock) for opening and shutting a door via structural matching, a card-type door operating device, a voice recognition door operating device, and an operating device for opening and shutting a door by entering a password, have been used.
However, recently, in order to solve problems caused by mechanical abrasion or the like of the mechanical door operating device among the above-described door operating devices and prevent inconvenience attributable to the loss of a key, a card-type door lock system or an electronic door lock system for opening and shutting a door by entering a password has been widely popularized and utilized.
Such an electronic door lock system is configured to open and shut a door by driving an electronic solenoid without requiring a key or a lock, and is configured such that a plurality of input buttons are provided on the outside of the door so that a user may enter a password having a predetermined number of digits, or provided to open and shut the door only if an entered password matches a pre-defined password when a user touches a card to the door.
However, such an electronic door look system is generally connected to an interphone or the like in a wired manner, so that when a doorbell is pressed by an outdoor visitor, if a person in an indoor area picks up a receiver for a call or presses a button for a call, a conversation with the outdoor visitor can be held while video for an outdoor area is being displayed on a monitor. Further, the electronic door lock system is configured such that when a door unlock button is pressed to open the door in an indoor area after identifying the visitor, an unlock signal is output from the main body of the door lock system present in the indoor area and then the door can be unlocked, and such that the operation of locking the door again from the indoor area in the unlocked state can be performed.
However, most current electronic door lock systems are problematic in that they are configured to perform only the function of opening and shutting a door, or only a function related to security, and in that a doorbell for calling an indoor area from an outdoor area is installed separately from a door lock, so that not only is man-hour required to install such a doorbell increased, but also the related cost, and the outer appearance of the door may be defiled due to the doorbell.
In order to solve the conventional problem, Korean Utility Model No. 400015 proposed an electronic door lock system provided with a doorbell. The electronic door lock system provided with a doorbell, disclosed in the above Korean Utility Model No. 400015, is configured to include an outdoor unit installed outside a door and provided with a keypad to enter a password required to open and shut the door, and an indoor unit installed inside the door and configured to open and shut the door in response to door unlock and lock signals based on the password input from the outdoor unit. The electronic door lock system is configured such that a doorbell button for calling a person in an indoor area is mounted in a predetermined place on the outdoor unit so that when the doorbell button is manipulated, a previously selected melody is output from a sound source storage unit in which one or more melodies are stored.
In the above-described conventional electronic door lock system, the doorbell is provided to be merely integrated with the door lock and a visitor must press the doorbell. Furthermore, a current electronic door lock system is installed such that an outdoor view is displayed on the monitor of an indoor video phone provided in the indoor area at the same time that the doorbell is operated and the displayed outdoor view is recorded.
Therefore, a problem arises in that when the doorbell is not pressed, the identity of a visitor cannot be known, and in that even if a person is present in the indoor area, it is difficult for the person to easily recognize that another person is coming in from the outdoor area when he or she opens the door using the numeric key area of the keypad provided on the door lock and enters the indoor area without pressing the doorbell.
Furthermore, the door lock is frequently used to input a password, so traces of use remain on the numeric key area. Thus, a problem arises in that a visitor can break into an indoor area using a numeric key area having traces of use, or can easily break into the indoor area using the numeric key area when a password is exposed due; to the carelessness of children.